Reduction of nitrite contaminants by selective hydrogenation

ABSTRACT

A process for selectively reducing nitrile contaminants in fluids such as water, methanol or hydrocarbon streams containing mono olefins and which contain minor amounts of contaminants comprising nitriles in the presence of hydrogen and a supported cobalt catalyst. In the olefin stream the nitrile contaminants are substantially reduced without substantial reduction of the mono olefins.

This is a divisional of Ser. No. 08/268,811, filed Jun. 30, 1994, nowU.S. Pat. No. 5,629,451.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the selective hydrogenation ofcontaminants contained in a light refinery stream.

2. Related Information

Dienes and nitriles are known catalyst poisons in processes using acidcatalysts. Many important processes in the petroleum industry requireacid catalysts. The production of gasoline octane enhancers such asmethyl tertiary butyl ether (MTBE) or tertiary amyl methyl ether (TAME)or catalyzed alkylation processes require acid catalysts.

Mixed refinery streams often contain a broad spectrum of olefiniccompounds. This is especially true of products from either catalyticcracking or thermal cracking processes. These olefinic compoundscomprise ethylene, acetylene, propylene, propadiene, methylacetylene,butenes, butadiene, etc. Many of these compounds are valuable,especially as feed stocks for chemical products. Ethylene, especially isrecovered. Additionally, propylene and the butenes are valuable.However, the olefins having more than one double bond and the acetyleniccompounds (having a triple bond) have lesser uses and are detrimental tomany of the chemical processes in which the single double bond compoundsare used, for example polymerization.

Refinery streams are usually separated by fractional distillation, andbecause they often contain compounds that are very close in boilingpoints, such separations are not precise. A C₅ stream, for instance, maycontain C₄ 's and up to C₈ 's. These components may be saturated(alkanes), unsaturated (mono-olefins), or poly-unsaturated (diolefins).Additionally, the components may be any or all of the various isomers ofthe individual compounds.

Several of the minor components (diolefins) in the feed will reactslowly with oxygen during storage to produce "gum" and other undesirablematerials. However, these components also react very rapidly in the TAMEprocess to form a yellow, foul smelling gummy material. Thus it is seento be desirable to remove these components whether the "light naphtha"cut is to be used only for gasoline blending by itself or as feed to aTAME process.

Diene contaminants can be removed by selective hydrogenation in thepresence of olefins. The most recommended catalyst being palladium on asupport, sometimes with promoters.

Hydrogenation is the reaction of hydrogen with a carbon-carbon multiplebond to "saturate" the compound. This reaction has long been known andis usually done at superatmospheric pressures and moderate temperaturesusing an excess of hydrogen over a metal catalyst. Among the metalsknown to catalyze the hydrogenation reaction are platinum, rhodium,cobalt, molybdenum, nickel, tungsten and palladium. Generally,commercial forms of catalyst use supported oxides of these metals. Theoxide is reduced to the active form either prior to use with a reducingagent or during use by the hydrogen in the feed. These metals alsocatalyze other reactions, most notably dehydrogenation at elevatedtemperatures. Additionally they can promote the reaction of olefiniccompounds with themselves or other olefins to produce dimers oroligomers as residence time is increased.

Selective hydrogenation of hydrocarbon compounds has been known forquite some time. Peterson, et al in "The Selective Hydrogenation ofPyrolysis Gasoline" presented to the Petroleum Division of the AmericanChemical Society in September of 1962, discusses the selectivehydrogenation of C₄ and higher diolefins. Boitiaux, et al in "NewestHydrogenation Catalyst", Hydrocarbon Processing, March 1985, presents anoverview of various uses of hydrogenation catalysts, including selectivehydrogenation, utilizing a proprietary bimetallic hydrogenationcatalyst.

The known method of removal of nitriles from hydrocarbon feeds involvesa water wash of the hydrocarbon feed. This requires a number of stages,depending on the relative solubility of the nitrile in water versushydrocarbon. These additional stages provide additional productioncosts. It is particularly difficult to remove propionitrile by waterwash. The additional stages required for water washing increasecomplexity and production costs. Although there is a substantial body ofart relating to the hydrogenation of nitriles to produce amines or otheramino compounds, there is no suggestion as to the fate of olefiniccompounds during those processes.

U.S. Pat. No. 2,449,036 teaches the hydrogenation of nitriles to primaryamines using nickel or cobalt catalysts providing the reduction is inthe presence of a strong aqueous basic solution in ethyl alcohol.

U.S. Pat. No. 3,565,957 discloses the reaction of nitrilotriacetonitrilewith hydrogen and a large amount of ammonia in the presence of acatalyst, chosen from a group consisting of nickel, cobalt, and rhodium.

U.S. Pat. No. 4,186,146 discloses the hydrogenation of aromatic nitrilesto the corresponding aminomethylbenzene derivatives in a solvent systemcontaining water, ammonia, and water miscible ether solvents using acobalt or nickel catalyst.

U.S. Pat. No. 4,235,821 discloses the hydrogenation of aliphaticnitriles in a solvent system of water, ammonia, and water miscibleethers using a ruthenium catalyst.

U.S. Pat. No. 4,739,120 teaches the hydrogenation of an organic nitrilegroup to a primary aminomethyl group in the presence of a rhodiumcatalyst, a basic substance, and a two-phase solvent system comprisingan immiscible organic solvent and water.

U.S. Pat. No. 5,075,506 describes a method for producing secondaryamines from fatty nitriles, with ammonia and hydrogen over a cobaltcatalyst promoted with zirconium. The catalyst may be supported onkieselguhr or other support. A second stage using the same catalyst butwithout ammonia, may be used to increase the proportion of secondaryamines.

It is an advantage of the present hydrogenation process to selectivelyhydrogenate contaminants with little if any saturation of the olefins.The absence of hydrogenation of olefins is an unexpected benefit, sincecobalt may used as a hydrogenation catalyst for olefins. A particularfeature of the present process is that nitriles are hydrogenated toamines, which can be removed easily by water wash, when compared tonitriles, due to fact that the low molecular wt. amines are very solublein water.

SUMMARY OF THE INVENTION

Briefly, the present invention is the removal of minor amounts ofnitrile contaminants from a fluid material by treatment with hydrogen inthe presence of a cobalt catalyst.

In one embodiment the present invention is a process for the treatmentof olefin containing hydrocarbon streams comprises feeding a lightnaphtha cut containing mono olefins and minor amounts of contaminantscomprising nitriles in the presence of hydrogen and a cobalt catalyst toreduce the contaminants without substantial reduction of the monoolefins. In a further embodiment of the present invention thehydrogenated stream is water washed to remove the amine products of thenitrile hydrogenation.

In another embodiment nitrile contaminants are removed from streamscomprising methanol, water and particularly methanol admixed with water.

DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS

Unexpectedly the nitrile contaminant is selectively and substantiallyremoved, while the olefin concentration is substantially unchanged. Thenitriles as contaminants are usually present in amounts of about 1 to5000 ppm which can be substantially reduced or essentially eliminated bythe present process.

The catalyst comprise a supported cobalt hydrogenation-dehydrogenationcatalyst, such as cobalt oxide or cobalt metal which may comprise fromabout 1 to 70% of the catalyst. A zirconium promoter may be present as acompound, such as zirconium oxide. The cobalt comprises 30 to 70 wt %,preferably about 40 to 60 wt % of the catalyst. The zirconium comprisesabout 1 to 5 wt. %, preferably about 2 to 3 wt. % of the catalyst. Thesupports include alumina, silica, titania, kieselguhr (also calleddiatomaceous earth, diatomite and infusorial) and the like.

The reaction is preferably carried out at mild temperatures and elevatedpressures. The process may generally operate at a temperature in therange of from about 30° to 200° C., more preferably about 60° to 80° C.The pressure may range from about 50 to 5000 psig, preferably from about200 to 300 psig. The hydrogen is maintained at an excess of thatutilized in the process. The rate of hydrogen addition is such as tomaintain an excess of hydrogen in the process. The residence time may beexpressed as the liquid hourly space velocity (LHSV) which may be in therange of 1-12.

The reaction may be carried out in any suitable reactor, including afixed bed straight pass reactor, positioned horizontally or vertically,with an up or down flow. A catalytic distillation reactor may also beused.

Suitable feeds for the present process are light refinery streamsgenerally comprising predominately hydrocarbons having up to 9 carbonatoms, e.g., C₃ to C₈ cuts, usually 4 to 8 linear carbon atoms,including both alkane and alkenes with the impurities noted above. Apreferred feed is a C₅ cut. The olefins may comprise from about 5 to 95%of the hydrocarbon stream, but generally comprises about 10 to 60%.

The C₅ 's in the feed are contained in a single "light naphtha" cutwhich contains everything from C₅ 's through C₈ 's and higher. Thismixture can easily contain 150 to 200 components and thus identificationand separation of the products are difficult.

The diene contaminants may comprise several percent of the feed and mayrequire prior or subsequent treatment to reduce them to very low levels.Dienes may be detrimental to the catalyst and are preferably removedbefore the present process is applied to a feed. For a similar reasonmercaptans and other sulfur compounds are preferably removed beforecarrying out the present process. However, the nitriles are usuallypresent in only a few parts per million, e.g. up to 100 parts permillion and their removal is almost complete, or at least to levelswhich substantially inhibit the poisoning of resin type catalysts.

Apparatus and General Process

The data that are the subject of this investigation were obtained froman insulated and thermostatted 2'×3/8" i.d. (30 ml. catalyst capacity)copper tube plug-flow reactor. Reaction temperature control wasmaintained by a steam jacket held at 610.54 torr vacuum (2.89 psia.,149.46 torr) for 140° F. reactions, 576.62 torr (3.72 psia., 192.37torr) for 150° reactions, and 514.87 torr (4.74 psia., 245.13 torr) for160° F. reactions. (Matheson Gas Products Model 3491 Vacuum Regulator,Precision Scientific, Inc. Vacuum Pump, Model 31 D-25; 0.88 L/min.pumping speed). Temperatures were attained utilizing a bayonet reboiler(Gaumer Co. Model 1P1N5RI, 1", 750 W, 120 VAC Stainless Steel Screw PlugHeater) immersed in the steam jacket water well. Thermostatic conditionswere maintained by variable transformer (Staco Type 3 PN1010, 120 VAC)control. An Omega Engineering thermocouple thermometer (ModelDP41-TC-A-S2) was used to monitor temperature from two regions: oneauxiliary bead-type thermocouple (K-type) strapped onto the steam jacketat the reactor exit (steam jacket front) and one grounded (OmegaEngineering Model KQIN-18; 1/8", K-type thermocouple) immersed into thewater well at the reactor entrance (steam jacket reflux) and in contactwith the steam. The reactor tube was operated "down-flow".

Mixed gas-liquid phase products were maintained in the liquid state bycollection in a sample cylinder that was filled from the bottom to topthrough a tube inserted at the cylinder top and extending to the bottomof the cylinder. Samples were removed into evacuated sample cylindersfrom the bottom of the loop collection cylinder. A back-pressureregulator (Go, Inc. Model P/N102765) was placed at the exit of thecollection system with a cracking pressure of about 150 psig.

Data were tabulated in the form of gas chromatographic integrations(Perkin-Elmer Model 8400 Capillary Column G.C. with a Supelco SeparationTechnologies Petrocol DH150 150 meter capillary column) and standardizedweight percentages from the appropriate response factors. Temperatureprogramming was reemployed as follows: isothermal at 0° C. for 24 min.,followed by a 10° C./min. ramp rate to 250° C. where it was held for 24min. Gas/liquid sample injections onto the GC column were made via a 1μL. loop sample valve connected directly to the injector port.

Additional items include three metering pumps that were used to controlthe flow of reactants into the reactor tube. Two pumps were usedseparately and also in conjunction to select a wide range of liquidhourly space (volume flow) velocities (Milton-Roy LDC Division Model2369-89; Duplex; max. 920 mL./hr. flowrate, Milton-Roy LDC DivisionModel 396-31 Simplex; 160 ml./hr. max. flowrate). A separate pump wasused to pump different reactants, i.e., pure methanol, into the samereactor tube (Eldex Laboratories Model A-60-VS fitted with both motorspeed and plunger stroke controls; 180 ml/hr. max. flow).

Feed tank pressures were maintained at about 50-75 psig, well below thepressure in the reactor tube and connecting 1/8" stainless steel tubingand fittings, in order to permit efficient differential pressure pumpoperation. Reactor system pressures were maintained by a back-pressureregulator (Mity-Mite Model S-91LW, 25-400 psig). Approximately 200-220psig N₂ (gauge: 0-400 psig) was applied at the back-pressure regulator(the reactor exit). There was no observable pressure gradient over thelength of the reactor tube. Additionally, a metering pump (EldexLaboratories, Inc. Model VS-60; 0.05-3.0 mL/hr., controlled both byvariable motor speed and manual micrometer-controlled piston stroke) wasemployed to add methanol to the TAME feed material for catalystregeneration (see below). Hydrogen flow rate, for thehydrodenitrogenation reaction, was controlled by a gas flow controller(Matheson Gas Products Flowmeter/Controller Model 8270; 0-500 sccm;calibrated for nitrogen gas). Initial reactions were typically carriedout under one of two hydrogen flow rates, 100 and 200 sccm, and at oneof two temperatures, 125° F. and 212° F. These reactions wereaccomplished by heating the reactor tube to the reaction temperature,setting the hydrogen flow rate, and then pumping hydrocarbon feed intothe reactor tube.

Catalyst

Each catalyst sample was pretreated by outgassing in a catalyst surfacearea apparatus at 250° C. in vacuo (10⁻⁵ torr) for 18 hours, then thecatalyst metal was chemically reduced by exposure to hydrogen at 250° C.for 18 hours (atmospheric pressure; approx. 760 torr). The sample wasthen allowed to cool to the ambient temperature in vacuo (approx. 10⁻⁴to 10⁻⁵ torr). A standard volume was evacuated, filled with CO, and thepressure was then recorded. The catalyst was heated to 200° C. in vacuoin order to desorb the chemisorbed CO.

Hydrogen chemisorption was accomplished by exposing the catalyst tohydrogen, then heating to 200° C., and then allowing it to cool to theambient temperature in vacuo. The standard volume was evacuated and thenfilled with hydrogen up to atmospheric pressure. The catalyst was thenexposed to the hydrogen. The sample volume containing the catalyst andhydrogen was heated to 100° C. and allowed to remain at this temperaturefor 1 hour. The sample was then allowed to cool to the ambienttemperature and the pressure was recorded.

Propionitrile (PN) and acetonitrile (ACN) are the most commoncontaminants.

EXAMPLE 1 Hydrotreatment for Nitrile Group Reduction PN and ACNHydrogenation in C₅ Naphtha Feedstock Contaminated with High DioleflnConcentrations.

    CH.sub.3 --C.tbd.N+2H.sub.2 →CH.sub.3 --CH.sub.2 --NH.sub.2

    CH.sub.3 --CH.sub.2 --C.tbd.N+2H.sub.2 →CH.sub.3 --CH.sub.2 --CH.sub.2 --NH.sub.2

The reactor is 3/8 inch×36 inch stainless steel tube. 35 ml of acatalyst cobalt oxide promoted with zirconium oxide supported onkieselguhr (United Catalyst Inc. G67 RS -54%Co/2.6%Zr on kieselguhroxide) is loaded in the reactor. The reactor is maintained attemperatures between 100° to 250° F. The pressure is maintained at 250psig. The LHSV is maintained between 3 to 5. Excess hydrogen ismaintained throughout the run. The olefin flow line and the reactorproduct line were analyzed by gas chromatograph. The olefin feedcomprised mostly C₅ olefins and saturated hydrocarbons with isoprene,acetonitrile, propionitrile and piperylenes as contaminants. The reactorproduct line analysis showed selective hydrogenation of dienecontaminants with little if any saturation of the C₅ olefins.

TABLE I provides a summary composition analysis of the olefin feed andreactor product for the run. The principal contaminant isoprene wasreduced by 96% only 0.4% of the olefin was lost.

                                      TABLE I                                     __________________________________________________________________________    H.sub.2     ACN                                                                              ACN   %-  PN PN    %-                                          (moles/hr.) ppm                                                                              (moles/hr.)                                                                         Conv.                                                                             ppm                                                                              (moles/hr.)                                                                         Conv.                                       __________________________________________________________________________    FEED  --    4.50                                                                             --    --  43.3                                                                             --                                                PRODUCT                                                                       #1.sup.a                                                                            .5354 2.20                                                                             8.04 × 10.sup.-4                                                              51.1%                                                                             29.4                                                                             5.90 × 10.sup.-3                                                              32.1%                                       #2.sup.b                                                                            .5354 0.02                                                                             8.04 × 10.sup.-4                                                              99.5%                                                                             0.17                                                                             5.90 × 10.sup.-3                                                              99.6%                                       #3    .5354 1.10                                                                             16.1 × 10.sup.-4                                                              75.6%                                                                             17.4                                                                             11.8 × 10.sup.-3                                                              59.8%                                       #4    .2677 0.00                                                                             8.04 × 10.sup.-4                                                              100%                                                                              0.02                                                                             5.90 × 10.sup.-3                                                              99.9%                                       #5    .2677 0.80                                                                             16.1 × 10.sup.-4                                                              82.2%                                                                             14.5                                                                             11.8 × 10.sup.-3                                                              66.5%                                       #6    .0857 3.00                                                                             8.04 × 10.sup.-4                                                              33.3%                                                                             34.1                                                                             5.90 × 10.sup.-3                                                              21.2%                                       #7    .0483 0.02                                                                             8.04 × 10.sup.-4                                                              99.5%                                                                             2.50                                                                             5.90 × 10.sup.-3                                                              92.2%                                       #8.sup.c                                                                            .5354 0.50                                                                             8.04 × 10.sup.-4                                                              47.0%                                                                             9.00                                                                             5.90 × 10.sup.-3                                                              79.2%                                       #9.sup.d                                                                            .5354 0.40                                                                             8.04 × 10.sup.-4                                                              88.9%                                                                             7.10                                                                             5.90 × 10.sup.-3                                                              83.6%                                       #10.sup.c                                                                           .5354 0.35                                                                             10.6 × 10.sup.-4                                                              92.2%                                                                             3.90                                                                             7.79 × 10.sup.-3                                                              91.0%                                       #11   .0937 0.025                                                                            10.6 × 10.sup.-4                                                              99.4%                                                                             0.029                                                                            7.79 × 10.sup.-3                                                              99.9%                                       #12.sup.f                                                                           .0937 4.50                                                                             10.6 × 10.sup.-4                                                              00.0%                                                                             43.3                                                                             7.79 × 10.sup.-3                                                               0.0%                                       #13.sup.g                                                                           .0937 4.50                                                                             9.32 × 10.sup.-4                                                              00.0%                                                                             43.3                                                                             6.85 × 10.sup.-3                                                               0.0%                                       __________________________________________________________________________     Reactor: Thermostatted, 3/8" × 36" reactor tube.                        Reactor Conditions: Pressure; 220-240 psi., .sup.a Reaction at 125.degree     F., .sup.b Reaction at 212° F., .sup.c Catalyst regenerated with       pure MeOH and sampled at 8 hrs. time of reaction at 150° F.; .sup.     Second sample at 24 hrs. time of reaction at 150° F. following         regeneration, .sup.e Catalyst regenerated with H.sub.2 /O.sub.2 treatment     at 240° F. followed by reaction at 115° F.; .sup.f Reaction     at 170° F., .sup.g Catalyst regenerated with H.sub.2 /O.sub.2          treatment at 340° F. followed by reaction at 115° F.            Liquid Flow Rate: Variable                                                    Hydrogen Flow Rate: Variable.                                                 Catalyst Charge: 30 mL (34.66 gms.) 54 Wt% Zr Supported on 1/8" kieselguh     extrudates.                                                                   Feed Composition: C.sub.5 feed containing approx. 0.00045 Wt% acetonitril     (ACN) or 4.5 ppm, approx. 0.00433 Wt% propionitrile (PN) or 43.3 ppm,         3.007 Wt% diolefin (isoprene; 2.39 Wt%, tpiperylene; .353 Wt%,                cpiperylene; .220 Wt%, butadiene; .0443 Wt%).                            

However, the catalyst deactivated over 8-24 hours run time. Regenerationwas possible by oxidation followed by hydrogenation at 340° F. Washingwith methanol allowed partial regeneration without oxidation.

Results were much better without high concentrations of dienes in thehydrocarbon feed.

EXAMPLE 2 Hydrotreatment for Nitrile Group Reduction ACN Hydrogenationon UCI G67RS (54%Co/2.6%Zr on kieselguhr oxide) in Pure Methanol at 150°F.

    CH.sub.3 --C.tbd.N+2H.sub.2 →CH.sub.3 --CH.sub.2 --NH.sub.2

The same apparatus was used. The results and process conditions are setout in TABLE II.

                  TABLE II                                                        ______________________________________                                                 ACN    ACN                                                                    ppm    (moles/hr.)                                                                             H.sub.2 (moles/hr.)                                                                    ACN Conversion                             ______________________________________                                        FEED     1100   2.42 × 10.sup.-3                                                                  --       --                                         PRODUCT                                                                       S-#8     109    2.42 × 10.sup.-3                                                                  1.875 × 10.sup.-3                                                                90.0%                                      S-#9     100    2.42 × 10.sup.-3                                                                  1.875 × 10.sup.-3                                                                90.1%                                      S-#10    1084   2.42 × 10.sup.-3                                                                  0.250 × 10.sup.-3                                                                1.50%                                      S-#11    1046   2.24 × 10.sup.-3                                                                  0.625 × 10.sup.-3                                                                5.00%                                      S-#12    894    2.42 × 10.sup.-3                                                                  1.250 × 10.sup.-3                                                                18.7%                                      S-#13    846    2.42 × 10.sup.-3                                                                  1.250 × 10.sup.-3                                                                23.1%                                      S-#14    674    2.42 × 10.sup.-3                                                                  1.875 × 10.sup.-3                                                                38.7%                                      S-#15    579    2.24 × 10.sup.-3                                                                  2.500 × 10.sup.-3                                                                47.0%                                      ______________________________________                                         Reactor: Thermostatted, 3/8" × 36" reactor tube.                        Reactor Conditions: Pressure; 220-240 psi., Temperature; 150° F.       Liquid Flow Rate: 3.9 LHSV.                                                   Hydrogen Flow Rate: Variable                                                  Catalyst Charge: 30 mL (36 gms.), 54 Wt% Co/2.6 WtZr Supported on 1/8"        kieselguhr extrudates.                                                        Feed Composition: 99.89% Methanol with 0.11% acetonitrile (ACN) by weight     Total Operating Time: Approx. 50-75 hours.                               

Table II shows ACN hydrogenation on UCI G67 RS (54%Co/2.6%Zr onkieselguhr oxide) in pure methanol feedstock at 150° F. ACN conversionincreases with hydrogen molar flow rate approaching 1:1 H₂ :ACN,Activity loss is observable in S-#14. Table II indicates very highactivity for the reaction of hydrogen with nitriles over a cobaltcatalyst (in methanol).

EXAMPLE 3 Hydrotreatment for Nitrile Group Reduction

PN Hydrogenation on UCI G67RS (54%Co/2,6%Zr on kieselguhr oxide) inMethanol Diluted with 0.05 W% Water.

    CH.sub.3 --CH.sub.2 --C.tbd.N+2H.sub.2 →CH.sub.3 --CH.sub.2 --CH.sub.2 --NH.sub.2

The same apparatus was used. The results and process conditions are setout in TABLE III,

                                      TABLE III                                   __________________________________________________________________________           PN ppm                                                                            PN (moles/hr.)                                                                        H.sub.2 (moles/hr.)                                                                  Conversion                                                                           Temp., °F.                            __________________________________________________________________________    FEED   146 --      --     --     --                                           PRODUCT                                                                       C-#40  11.5                                                                              1.871 × 10.sup.-4                                                               26.85 × 10.sup.-3                                                              92.1%  212                                          C-#41  16.3                                                                              1.871 × 10.sup.-4                                                               26.855 × 10.sup.-3                                                             88.8%  212                                          C-#42  3.9 .9383 × 10.sup.-4                                                               21.42 × 10.sup.-3                                                              97.3%  212                                          C-#43  35.7                                                                              .9383 × 10.sup.-4                                                               21.42 × 10.sup.-3                                                              75.5%  250                                          C-#44  22.6                                                                              .9383 × 10.sup.-4                                                               21.42 × 10.sup.-3                                                              84.5%  250                                          C-#45  45.5                                                                              .9383 × 10.sup.-4                                                               21.42 × 10.sup.-3                                                              69.2%  250                                          C-#46  2.2 .9383 × 10.sup.-4                                                               16.065 × 10.sup.-3                                                             98.5%  150                                          C-#47  3.9 .9383 × 10.sup.-4                                                               16.06 × 10.sup.-3                                                              97.3%  150                                          C-#48  0.0 .9383 × 10.sup.-4                                                               16.06 × 10.sup.-3                                                              100%   150                                          C-#49  0.0 .9383 × 10.sup.-4                                                               10.71 × 10.sup.-3                                                              100%   150                                          C-#50  0.0 .9383 × 10.sup.-4                                                               10.71 × 10.sup.-3                                                              100%   150                                          C-#51  0.0 .9383 × 10.sup.-4                                                               10.71 × 10.sup.-3                                                              100%   150                                          C-#52  0.0 1.871 × 10.sup.-4                                                               10.71 × 10.sup.-3                                                              100%   150                                          C-#53  0.0 2.807 × 10.sup.-4                                                               10.71 × 10.sup.-3                                                              100%   150                                          C-#54  0.0 2.807 × 10.sup.-4                                                               10.71 × 10.sup.-3                                                              100%   150                                          C-#55  0.0 4.679 × 10.sup.-4                                                               10.71 × 10.sup.-3                                                              100%   150                                          C-#56  0.0 4.679 × 10.sup.-4                                                               16.06 × 10.sup.-3                                                              100%   150                                          C-#57  0.0 4.679 × 10.sup.-4                                                               21.42 × 10.sup.-3                                                              100%   150                                          C-#58  0.0 4.679 × 10.sup.-4                                                               21.42 × 10.sup.-3                                                              100%   150                                          C-#59  0.0 1.871 × 10.sup.-4                                                               18.74 × 10.sup.-3                                                              100%   175                                          C-#60  0.0 2.807 × 10.sup.-4                                                               18.74 × 10.sup.-3                                                              100%   175                                          C-#61  0.0 4.679 × 10.sup.-4                                                               18.74 × 10.sup.-3                                                              100%   175                                          __________________________________________________________________________     Reactor: Thermostatted, 3/8" × 36" reactor tube.                        Reactor Conditions: Pressure; 220-240 psi., Temperature; Variable             °F.                                                                    Liquid Flow Rate: Variable LHSV.                                              Hydrogen Flow Rate: Variable                                                  Catalyst Charge: 30 mL (36 gms.), 54 Wt% Co/2.6 Zr Supported on 1/8"          kieselguhr extrudates.                                                        Feed Composition: 99.804% Methanol, 0.05% water with 0.146% propionitrile     (PN) by weight.                                                               Total Operating Time: Approx. 50-75 hours.                               

Table III shows PN hydrogenation on UCI G67 RS (54%Co/2.6%Zr onkieselguhr oxide) in pure methanol diluted with 0.05% water. Extent ofreaction increased with decreasing temperature. Hydrogenation activityloss was not observable at the relatively low PN concentration in thepresence of added water.

EXAMPLE 4 Hydrotreatment for Nitrile Group Reduction PN Hydrogenation onUCI G67RS (54%Co/2.6%Zr on kieselguhr oxide) in Methanol that was HighlyDiluted with Water.

    CH.sub.3 --CH.sub.2 --C.tbd.N+2H.sub.2 →CH.sub.3 --CH.sub.2 --CH.sub.2 --NH.sub.2

The same apparatus was used. The results and process conditions are setout in TABLE IV.

                  TABLE IV                                                        ______________________________________                                               PN ppm                                                                              PN (moles/hr.)                                                                           H.sub.2 (moles/hr.)                                                                      Conversion                                 ______________________________________                                        FEED     1453    --         --       --                                       PRODUCT                                                                       CS#2.sup.a                                                                             115     9.36 × 10.sup.-3                                                                   16.06 × 10.sup.-3                                                                92.1%                                    CS#3     89      6.682 × 10.sup.-3                                                                  16.06 × 10.sup.-3                                                                93.9%                                    CS#4.sup.b                                                                             68      1.87 × 10.sup.-3                                                                   16.06 × 10.sup.-3                                                                95.3%                                    CS#5     81      3.74 × 10.sup.-3                                                                   16.06 × 10.sup.-3                                                                94.4%                                    CS#6.sup.c                                                                             46      1.87 × 10.sup.-3                                                                   16.06 × 10.sup.-3                                                                96.8%                                    CS#7     104     9.36 × 10.sup.-3                                                                   16.06 × 10.sup.-3                                                                92.8%                                    ______________________________________                                         Reactor: Thermostatted, 3/8" × 36" reactor tube.                        Reactor Conditions: Pressure; 220-240 psi., Temperature; .sup.a               175° F., .sup.b 212° F., .sup.c 150° F.                  Liquid Flow Rate: Constant.                                                   Hydrogen Flow Rate: Variable                                                  Catalyst Charge: 30 mL (36 gms.), 54 Wt% Co/2.6 WtZr Supported on 1/8"        kieselguhr extrudates.                                                        Feed Composition: 66.57% Water, 33.28% methanol with .1453% propionitrile     (PN) by weight.                                                               Total Operating Time: Approx. 90-115 hours (See Table III).              

Table IV shows PN hydrogenation on UCI G67 RS (54%Co/2.6%Zr onkieselguhr oxide extrudates) methanol that was highly diluted withwater. High PN conversion of an initially very high PN concentration wasaccomplished at moderate temperatures in an aqueous solution.Hydrogenation catalyst activity loss was not observed. A 2H₂ :1PN orgreater ratio was attained; however, complete hydrogenation was notfound at any LHSV (contact time). Tables III and IV show 100 percentconversion of nitriles using methanol diluted with water as solvent.This relates to the patent or extraction of PN with methanol H₂ O fromC₅ 's.

EXAMPLE 5 Hydrotreatment for Nitrile Group Reduction PN Hydrogenation onUCI G67RS (54%Co/2.6%Zr on kieselguhr oxide) in Uncontaminated, lightnaphta cut C₅ Feedstock

    CH.sub.3 --CH.sub.2 --C.tbd.N+2H.sub.2 →CH.sub.3 --CH.sub.2 --CH.sub.2 --NH.sub.2

The same apparatus was used. The results and process conditions are setout in TABLE V.

                  TABLE V                                                         ______________________________________                                                      PN                                                                      PN ppm                                                                              (moles/hr.)                                                                             H.sub.2 (moles/hr.)                                                                      Conversion                                 ______________________________________                                        FEED      10      --        --       --                                       DS-#1-DS-#26.sup.a                                                                      0.0     >0.7 × 10.sup.-7                                                                  >0.027   95+%                                     FEED      12      --        --       --                                       DS-#27-DS-#31.sup.b                                                                     0.0     >0.8 × 10.sup.-7                                                                  >0.027   95+%                                     DS-#32.sup.c                                                                            10.9    >4.5 × 10.sup.-7                                                                  >0.027   9.3+%                                    DS-#33.sup.d                                                                            4.26    >3.4 × 10.sup.-7                                                                  >0.027    64.5%                                   ______________________________________                                         Reactor: Thermostatted, 3/8" × 36" reactor tube.                        Reactor Conditions: Pressure; 240 psi., Temperature; .sup.1 50°F.      Liquid Flow Rate: Variable LHSV; .sup.a,b 3, .sup.c 17, .sup.d 12.7.          Hydrogen Flow Rate: Excess (greater than 1.0 × 10.sup.+4 /1 =           2*H.sub.2 /Nitrile).                                                          Catalyst Charge: 30 mL (36 gms.), 54 Wt% Co/2.6 Wt% Zr Supported on 1/8"      kieselguhr extrudates.                                                        Feed Composition: approx. 10 ppm; 0.0010 Wt% propionitrile (PN) by weight     or 12 ppm; 0.0012 Wt% propionitrile (PN) by wight, dienefree C.sub.5 feed     Total Operating Time: Approx. 1075 hours.                                

Table V shows PN hydrogenation on UCI G67 RS (54%Co/2.6%Zr on kieselguhroxide extrudates) in TAME process C₅ feedstock. PN hydrogenation atrelatively low initial PN concentration appeared to be very sensitive toLHSV (contact time). Hydrogenation catalyst activity loss was notevident.

EXAMPLE 6 Hydrotreatment for Nitrile Group Reduction PN Hydrogenation onUCI T303 (5%Co on alumina) in light naphtha cut C₅ Feedstock that wasHighly Contaminated with Organic Sulfur (Ethylmercaptan Poison

    CH.sub.3 --CH.sub.2 --C.tbd.N+2H.sub.2 →CH.sub.3 --CH.sub.2 --CH.sub.2 --NH.sub.2

The same apparatus was used. The results and process conditions are setout in TABLE VI.

                  TABLE VI                                                        ______________________________________                                        PN ppm      PN (moles/hr.)                                                                           H.sub.2 (moles/hr.)                                                                       Conversion                                 ______________________________________                                        FEED   29.0     --         --        --                                       DS-T1X.sup.a                                                                         0.0      2.0 × 10.sup.-7                                                                    >0.027    99.9+%                                   DS-T2X 0.0      4.9 × 10.sup.-7                                                                    >0.027    99.9+%                                   DS-T3X 0.48     6.7 × 10.sup.-7                                                                    >0.027    98.3%                                    DS-T4X 0.0      2.0 × 10.sup.-7                                                                    >0.027    99.9+%                                   DS-T6X 28.91    5.6 × 10.sup.-7                                                                    >0.027    0.30%                                    DS-T7X.sup.b                                                                         27.51    5.6 × 10.sup.-7                                                                    >0.027    5.10%                                    DS-T8X.sup.c                                                                         0.0      5.6 × 10.sup.-7                                                                    >0.027    99.9+%                                   DS-T10X.sup.d                                                                        14.43    5.6 × 10.sup.-7                                                                    >0.027    50.2%                                    DS-T11X.sup.c                                                                        5.05     1.6 × 10.sup.-7                                                                    >0.027    82.6%                                    DS-T12X                                                                              6.46     1.5 × 10.sup.-7                                                                    >0.027    77.7%                                    ______________________________________                                         Reactor: Thermostatted, 3/8" × 36" reactor tube.                        Reactor Conditions: Pressure; 240 psi., Temperature; .sup.a1 50°F.     b189° F., .sup.d 275° F.                                        Liquid Flow Rate: Variable LHSV                                               Hydrogen Flow Rate: Excess (greater than 1.0 × 10.sup.+4 /1 =           2*H.sub.2 /Nitrile).                                                          Catalyst Charge: 30 mL (36 gms.), UCI T303 catalyst; 5 Wt% Co Supported o     7-12 mesh alumina spheres.                                                    Feed Composition: approx. 0.0029% propionitrile (PN) by weight, or 29 ppm     dienefree C.sub.5 contaminated with 420 ppm organic sulfur (ethyl             mercaptan source).                                                            Total Operating Time: Approx. 510 hours. Effluent was sampled at irregula     intervals with continuous, 24 hoursa-day operation. A rapid conversion        loss may appear as a result of `breakthrough` after several days reaction     i.e., between effluent analyses.                                         

Table VI shows PN hydrogenation on UCI T303 (5%Co on alumina) in TAMEProcess C₅ feedstock. The effluent was sampled at irregular intervalswith continuous, 24 hours-a-day operation. A rapid conversion lossappeared and may be a result of `breakthrough` after several daysreaction, i.e., between effluent analyses. Presence of sulfur compoundscause slow deactivation but recovery of activity seems possible.

The invention claimed is:
 1. A process for the reduction of minorcontaminant amounts of nitriles comprising treating a fluid materialconsisting essentially of methanol and containing said contaminant withhydrogen in the presence of a cobalt catalyst at a pressure in the rangeof 50 to 5000 psig at a temperature in the range of 30° to 200° C. 2.The process according to claim 1 wherein cobalt comprises 2 to 70 wt %of said catalyst.
 3. The process according to claim 2 wherein cobaltcomprises about 40 to 60 wt % of said catalyst.
 4. The process accordingto claim 2 wherein zirconium comprises about 1 to 5 wt. % of thecatalyst.
 5. The process according to claim 2 wherein zirconiumcomprises about 2 to 3 wt. % of the catalyst.
 6. The process accordingto claim 2 carried out at a temperature in the range of 30° to 200° C.7. The process according to claim 6 carried out at 50 to 300 psig. 8.The process according to claim 6 carried out at a temperature in therange of 50° to 100° C.
 9. The process according to claim 1 carried outat an LHSV of 2 to
 12. 10. The process of claim 5 wherein said cobaltand zirconium are supported.
 11. The process of claim 10 wherein saidsupport comprises kieselguhr.
 12. The process according to claim 10wherein said support comprises alumina.